=Euclid filters
stole extinction.py from specutils.  need for constructing SEDs from CatSim
Removing voigt12 filters.
added relative alignment plot
updated case study plots
=updated case study for seeing
fonts etc.
bug fix
made gparam_to_galsim private
added extinction to __init__
chromatic seeing now has variable power law index
removed lost dependency
use propID to isolate WFD survey
updated plotting
separated some utils to phot.py
compare spec-zs to photo-zs
add bulge/disk separation for color gradients calculation
add i-band plots to main() function